In mobile telecommunications backhaul, service providers are mainly attracted by solutions which provide high available bandwidth (>1 Gb/s), with high efficiency, at low operating cost. Free space optical (FSO) communications offers fibre like bandwidth, while reducing the cost per transmitted bit as compared to a fibre based system. To realize a mobile backhaul connection for carrier class applications, 99.999% link reliability is mandatory. 99.98% link availability using transparent FSO terminals capable of transmitting up to 1.2 Tb/s capacity traffic has recently been reported by E. Ciaramella et al, “1.28-Tb/s (32×40 Gb/s) Free-Space Optical WDM Transmission System”, Photonics Technology Letters, vol. 21, no. 16, 15 Aug. 2009, pages 1121-1123.